From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=50132 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OZLkm-0007o4-A2 for qemu-devel@nongnu.org; Thu, 15 Jul 2010 06:33:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OZLkj-0003JH-Qi for qemu-devel@nongnu.org; Thu, 15 Jul 2010 06:33:20 -0400 Received: from mail.codesourcery.com ([38.113.113.100]:54300) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OZLkj-0003Iy-JA for qemu-devel@nongnu.org; Thu, 15 Jul 2010 06:33:17 -0400 From: Paul Brook Subject: Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support Date: Thu, 15 Jul 2010 11:33:14 +0100 References: <1279086307-9596-1-git-send-email-eduard.munteanu@linux360.ro> <201007142113.44913.paul@codesourcery.com> <4C3E2C2E.70507@codemonkey.ws> In-Reply-To: <4C3E2C2E.70507@codemonkey.ws> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201007151133.14493.paul@codesourcery.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Joerg Roedel , Eduard - Gabriel Munteanu , qemu-devel@nongnu.org, kvm@vger.kernel.org, avi@redhat.com > > Depending how the we decide to handle IOMMU invalidation, it may also be > > necessary to augment the memory_map API to allow the system to request a > > mapping be revoked. However this issue is not specific to the IOMMU > > implementation. Such bugs are already present on any system that allows > > dynamic reconfiguration of the address space, e.g. by changing PCI BARs. > > That's why the memory_map API today does not allow mappings to persist > after trips back to the main loop. Sure it does. If you can't combine zero-copy memory access with asynchronous IO then IMO it's fairly useless. See e.g. dma-helpers.c Paul